Assessment of the Doppler Radar for Airport Weather (DRAW) system in Japan as a research tool for studying typhoon

The purpose of this study is to demonstrate the usefulness of the Doppler Radar for Airport Weather (DRAW) system as a research tool for studying typhoon. The DRAW, which started its operation in 1996 as a wind shear detection and warning platform in Japan (Ishihara and Hata 1995), has been installed at eight major airports in Japan. It has a 120-km observation range, a 0.7 azimuth resolution, and a pulse length of 1.0 micro-sec providing independent data points every 150 m in range. A volume scan update rate of 6 min and a 75-s time series of PPI scan of the lowest elevation, 0.8, can be obtained. The DRAW velocity dealiasing algorithm (Kusunoki et al. 1996) correctly dealiases velocities even in a strong wind associated with typhoon. All of the DRAWs are located less than 30km from shore, therefore, they can provide mesoscale details of wind and precipitation structure at landfall, which is of great importance because most typhoon damage occurs in the coastal zone. Prior to the installation of the DRAW, high-resolution Doppler velocity data could be obtained only from research radars employed during limited field programs. Although the above useful features, the typhoon observations with DRAW are limited by the range of 120km and much shorter ranges to the detailed typhoon boundary layer in addition to the large expanses in radar coverage. In this study, we particularly aim at assessing opportunity for detecting typhoon circulations and precipitations with the DRAW. For our purpose, 1 hour positions and intensities are provided from an interpolation of the best-track archives (1990-2004) of the Japan Meteorological Agency. With these data, the probability (frequency) of detection of circulation and precipitation around typhoon centers are simulated.